Good day!

We have siemens Active Front End (AFE) 6SE 7138-6EG80-2BAO -Z in our contaniner crane. We had so much failure in filter circuit, that is Contactor (K7) and 4 numbers of capacitor fail with in 3 times. Siemens service engineer In india can't able to solve the problem.

Anybody having solution or any body facing this problem?

Simovert Master Drive AFE 6SE 7138-6EG80-2BAO -Z Supply I/P 3AC 50-60 Hz 380-460V O/P DC 600-727 V Ac current 817 Amps

 

Hello Nallan,

Food for thought... Is your Simovert drive being fed from an Isolated delta transformer system?
If so, check for a grounded supply leg. The adjacent phases can increase voltage in reference to ground with a partially or fully grounded phase. I've repaired many drives where the suppressor capacitors and transient suppressor MOV's have blown apart because of a grounded leg on the supply voltage. They are connected from phase to earth ground within the drive. When the phase voltage exceeds the component rating, they will short out.

Hope this helps,
Rick Macy

 

We verified the Earthing leg and found Ok

 

Hello Nalla,

Pls furnish more info - is your supply from a engine power pack or from the utility??

Which is the crane supplier and who engineer the system for it??

then I can let you know how to overcome it.

JEFF (AFE PROBLEM SOLVED)

 

Hi Nalla,

probably your power grid is suffering from voltage fluctuations which are beyond the AFE's capability of handling. Please refer to the catalogue DA65.10 (page 6/24 from english edition 2004), which says if the power dips are up to 50% (lasting 20 ms - 60 secs), a special auxilliary power supply must be provided. The contacts in K7 will wear down, so put a small UPS for the power supply of the AFE control section, and replace the worn-out K7.
That should fix your problem.

good luck
Rob

 

Nalla,

1) What are capacitor rating (uF or kVAr) and voltage rating?

2) Are they connected phase-to-phase? Or phase-to-earth?

Oops, I forgot the most important questions of all.

3) Are capacitors connected on delta-side? Then, please confirm that they are connected phase-to-earth!

4) Are failures random? Or is one phase more apt to fail?

Rergards,
Phil Corso, PE
[email protected] or [email protected]

 

1) Power feed from 3.3 KV sub station
2) Noell and complete siemens system
Siemens Active front end.

Capacitor type
MKK480 -D-*,3 -01
3*38.4 Micr f

 

Capacitor failures could be the result of open circuits in the balancing resistor circuits (from vibrations). Also, ripple current and voltages (DC Link Voltage) have a huge impact on the capacitors.

(The dielectrics must first be properly formed.)

Regeneration back into the drive from over-hauling loads results in a rapid rise of the DC-Link - which can also cause failures. Make sure that a chopper circuit is in place across the DC LINK (with the proper threshold settings).

 

In response to Phil Corso's questions:

Good Day!

>>What are capacitor rating (uF or kVAr) and voltage rating?

Make: EPCOS
TYPE: MKK480-D-8.3-01
4RB5
B25667A4117A365
CN:3*38.4MICRO F +-5%
480V 8.3.KVAR -10 KVAR
465V 7.8.KVAR -9.4 KVAR
440V 7.0.KVAR -8.4 KVAR

>>2) Are they connected phase-to-phase? Or phase-to-earth?

Phase to Phase Only

>>3) Are capacitors connected on delta-side? Then, please confirm that they are connected phase-to-earth!

Delta side and One Phase Earth

>>4) Are failures random? Or is one phase more apt to fail?

It is Random Only every 3 months.

Regards
Nallan

 

Responding to Nallan's Sep 3, 12:19pm comments... there is some confusion on my part. Please confirm, refute, or clarify my understanding of your system configuration:

1) An isolation transformer is installed on each drive? It's primary/secondary winding configuration is delta/delta?

2) Is it floating, meaning that, there is no intentional earthing connection from neither the primary nor secondary terminals, to ground?

3) What is meant by "One Phase Earth"? Do you mean that 3 caps are installed ph-ph, example A-B. B-C, C-A, and a 4th is installed from one
terminal to earth, example A-earth?

4) What are phase-to-phase voltage measurements?

5) What are phase-to-earth voltage measurements?

6) Do any protective fuses (or circuit breakers) operate at the time of the cap failures?

7) Your Jul 18, 10:25pm reply to Rick Macy mentioned "Earthing leg...
OK!" Can you clarify?

Regards,
Phil Corso, PE {Boca Raton, FL, USA}
[[email protected]] ([email protected])